Nissan Quest E52. Manual - part 507

EC-238

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

P014C, P014D, P014E, P014F, P015A, P015B, P015C, P015D A/F SENSOR 1

1.

Clear the mixture ratio self-learning value. Refer to 

EC-139, "Work Procedure"

.

2.

Run engine for at least 10 minutes at idle speed.

Is the 1st trip DTC P0171, P0172, P0174 or P0175 detected? Is it difficult to start engine?

YES

>> Perform trouble diagnosis for DTC P0171, P0174 or P0172, P0175. Refer to 

EC-241, "DTC Logic"

or 

EC-245, "DTC Logic"

.

NO

>> GO TO 5.

5.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY

1.

Disconnect A/F sensor 1 harness connector.

2.

Turn ignition switch ON.

3.

Check the voltage between A/F sensor 1 harness connector and ground.

Is the inspection result normal?

YES

>> GO TO 7.

NO

>> GO TO 6.

6.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 POWER SUPPLY CIRCUIT

1.

Turn ignition switch OFF.

2.

Disconnect IPDM E/R harness connector.

3.

Check the continuity between A/F sensor 1 harness connector and IPDM E/R harness connector.

Is the inspection result normal?

YES

>> Perform the trouble diagnosis for power supply circuit.

NO

>> Repair or replace error-detected parts.

7.

CHECK A/F SENSOR 1 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Turn ignition switch OFF.

2.

Disconnect ECM harness connector.

3.

Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

DTC

A/F sensor 1

Ground

Voltage

Bank

Connector

Terminal

• P014C
• P014D
• P015A
• P015B

1

F27

4

Ground

Battery voltage

• P014E
• P014F
• P015C
• P015D

2

F64

4

DTC

A/F sensor 1

IPDM E/R

Continuity

Bank

Connector

Terminal

Connector

Terminal

• P014C
• P014D
• P015A
• P015B

1

F27

4

F12

57

Existed

• P014E
• P014F
• P015C
• P015D

2

F64

4

P014C, P014D, P014E, P014F, P015A, P015B, P015C, P015D A/F SENSOR 1

EC-239

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

C

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E

F

G

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EC

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4.

Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector
and ground.

5.

Also check harness for short to power.

Is the inspection result normal?

YES

>> GO TO 8.

NO

>> Repair open circuit, short to ground or short to power in harness or connectors.

8.

CHECK AIR FUEL RATIO (A/F) SENSOR 1 HEATER

Check air fuel ratio (A/F) sensor 1 heater. Refer to 

EC-173, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 9.

NO

>> Replace malfunctioning air fuel ratio (A/F) sensor 1. Refer to 

EM-33, "Exploded View"

.

9.

CHECK MASS AIR FLOW SENSOR

Check both mass air flow sensor (bank 1 and bank 2).
Refer to 

EC-181, "Component Inspection"

.

Is the inspection result normal?

YES

>> GO TO 10. 

NO

>> Replace malfunctioning mass air flow sensor. Refer to 

EM-26, "Exploded View"

.

10.

CHECK PCV VALVE

Check PCV valve. Refer to 

EC-459, "Work Procedure"

.

Is the inspection result normal?

DTC

A/F sensor 1

ECM

Continuity

Bank

Connector

Terminal

Connector

Terminal

• P014C
• P014D
• P015A
• P015B

1

F27

1

F8

69

Existed

2

73

• P014E
• P014F
• P015C
• P015D

2

F64

1

77

2

81

DTC

A/F sensor 1

Ground

Continuity

Bank

Connector

Terminal

• P014C
• P014D
• P015A
• P015B

1

F27

1

Ground

Not existed

2

• P014E
• P014F
• P015C
• P015D

2

F64

1

2

DTC

ECM

Ground

Continuity

Bank

Connector

Terminal

• P014C
• P014D
• P015A
• P015B

1

F8

69

Ground

Not existed

73

• P014E
• P014F
• P015C
• P015D

2

77

81

EC-240

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

P014C, P014D, P014E, P014F, P015A, P015B, P015C, P015D A/F SENSOR 1

YES

>> GO TO 11.

NO

>> Repair or replace PCV valve. Refer to 

EM-52, "Exploded View"

.

11.

CHECK INTERMITTENT INCIDENT

Check intermittent incident. Refer to 

GI-42, "Intermittent Incident"

.

Is the inspection result normal?

YES

>> Replace malfunctioning air fuel ratio (A/F) sensor 1. Refer to 

EM-33, "Exploded View"

.

NO

>> Repair or replace error-detected parts.

P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

EC-241

< DTC/CIRCUIT DIAGNOSIS >

[VQ35DE]

C

D

E

F

G

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EC

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P0171, P0174 FUEL INJECTION SYSTEM FUNCTION

DTC Logic

INFOID:0000000009651087

DTC DETECTION LOGIC

With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from A/F sensor 1. The ECM calculates
the necessary compensation to correct the offset between the actual and the theoretical ratios.
In case the amount of the compensation value is extremely large (the actual mixture ratio is too lean), the
ECM judges the condition as the fuel injection system malfunction and illuminates the MIL (2 trip detection
logic).

DTC CONFIRMATION PROCEDURE

1.

PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following before conduct-
ing the next test.
1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON.

3.

Turn ignition switch OFF and wait at least 10 seconds.

>> GO TO 2.

2.

PERFORM DTC CONFIRMATION PROCEDURE-I

1.

Clear the mixture ratio self-learning value. Refer to 

EC-139, "Work Procedure"

.

2.

Start engine.

Is it difficult to start engine?

YES

>> GO TO 3.

NO

>> GO TO 4.

3.

RESTART ENGINE

If it is difficult to start engine, the fuel injection system has a malfunction, too.
Crank engine while depressing accelerator pedal.
NOTE:
• When depressing accelerator pedal three-fourths (3/4) or more, the control system does not start the

engine. Do not depress accelerator pedal too much.

Does engine start?

YES

>> Proceed to 

EC-242, "Diagnosis Procedure"

.

NO

>> Check exhaust and intake air leakage visually.

4.

PERFORM DTC CONFIRMATION PROCEDURE-II

1.

Keep engine idle for at least 5 minutes.

2.

Check 1st trip DTC.

Is 1st trip DTC detected?

Sensor

Input signal to ECM

ECM function

Actuator

A/F sensor 1

Density of oxygen in exhaust gas
(Mixture ratio feedback signal)

Fuel injection control

Fuel injector

DTC No.

Trouble diagnosis name

DTC detecting condition

Possible cause

P0171

Fuel injection system too 
lean (bank 1)

• Fuel injection system does not operate properly.
• The amount of mixture ratio compensation is too 

large. (The mixture ratio is too lean.)

• Intake air leakage
• A/F sensor 1
• Fuel injector
• Exhaust gas leakage
• Incorrect fuel pressure
• Lack of fuel
• Mass air flow sensor
• Incorrect PCV hose connection

P0174

Fuel injection system too 
lean (bank 2)